Binary search (13.1) binary search: Locates a target value in a sorted array/list by successively eliminating half of the array from consideration. How many elements will it need to examine? O(log N) Can be implemented with a loop or recursively Example: Searching the array below for the value 42: index 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 value -4 20 22 25 30 36 42 50 56 68 85 92 103 min mid max

Collections class Method name Description binarySearch(list, value) returns the index of the given value in a sorted list (< 0 if not found) copy(listTo, listFrom) copies listFrom's elements to listTo emptyList(), emptyMap(), emptySet() returns a read-only collection of the given type that has no elements fill(list, value) sets every element in the list to have the given value max(collection), min(collection) returns largest/smallest element replaceAll(list, old, new) replaces an element value with another reverse(list) reverses the order of a list's elements shuffle(list) arranges elements into a random order sort(list) arranges elements into ascending order

The compareTo method (10.2) The standard way for a Java class to define a comparison function for its objects is to define a compareTo method. Example: in the String class, there is a method: public int compareTo(String other) A call of A.compareTo(B) will return: a value < 0 if A comes "before" B in the ordering, a value > 0 if A comes "after" B in the ordering, 0 if A and B are considered "equal" in the ordering.

Interfaces (9.5) interface: A list of methods that a class can promise to implement. Inheritance gives you an is-a relationship and code sharing. A Lawyer can be treated as an Employee and inherits its code. Interfaces give you an is-a relationship without code sharing. A Rectangle object can be treated as a Shape but inherits no code. Analogous to non-programming idea of roles or certifications: "I'm certified as a CPA accountant. This assures you I know how to do taxes, audits, and consulting." "I'm 'certified' as a Shape, because I implement the Shape interface. This assures you I know how to compute my area and perimeter."

Comparable (10.2) public interface Comparable<E> { public int compareTo(E other); } A class can implement the Comparable interface to define a natural ordering function for its objects. A call to your compareTo method should return: a value < 0 if the this object comes "before" other one, a value > 0 if the this object comes "after" other one, 0 if the this object is considered "equal" to other.